ALIMENTATION AND DIGESTION 133 



secretion of gastric juice is secured, in turn, by stimulation of 

 the mucous membrane of the stomach by the peptones which 

 the psychic secretion has formed from the proteins of the food ; 

 and, finally, that the chemical action of the gastric juice is 

 aided by the peculiar contractions of the muscular coat of the 

 stomach. All these agencies working together deliver the food 

 to the intestine in a finely divided state, well adapted and in- 

 deed absolutely necessary to secure the proper contact of the 

 food with the pancreatic juice, the bile, and the intestinal juice. 



The flow of pancreatic juice, in turn, is partly the result 

 of the action of the hydrochloric acid of the chyme on the 

 walls of the intestine, while the efficiency of the action of the 

 pancreatic enzymes depends upon the simultaneous action of 

 the bile and the intestinal juice ; lastly, the chemical action 

 of these juices, as well as the final act of absorption, requires 

 the cooperation of the muscular coat. Healthy conditions 

 with respect to bacterial action similarly depend upon all 

 else occurring as it should. Digestion, in short, is a chain of 

 events, each depending upon those which have gone before 

 and, to a large extent, upon those which are taking place at 

 the same time. 



Keeping these facts in mind, it is easy to appreciate the 

 possibility of diarrhea or constipation, the latter consisting 

 in the retention of wastes, the poisonous constituents of which 

 may be absorbed into the body and cause discomfort, head- 

 aches, and malaise. When all the digestive processes work 

 together properly there should be a perfectly natural and 

 regular evacuation of the bowels. The frequency of such 

 evacuation varies somewhat and is largely a matter of habit ; 

 with some 'people it is twice a day, with others once every 

 other day, but with the vast majority it is normally once every 

 day and at about the same time. Where this is not the case 

 there is reason to believe that some part of the work of diges- 

 tion is not being properly performed. The trouble is not 

 ordinarily in the mechanism governing the actual discharge 



